New poraspids (Agnatha, Heterostraci) from the Early Devonian of the western United States

Elliott, David K.; Petriello, Michael A.

doi:10.1080/02724634.2011.557113

Cited by 19 publications

(28 citation statements)

References 23 publications

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“…They have been interpreted as apex predators in shallow water near shore basins [3][4][5]. A study of the chelicera of the pterygotid Acutiramus cummingsi (Pterygotidae), however, concluded that it could at best 'trap, grasp and slice soft-bodied and relatively weak prey' [6].…”

Section: Introductionmentioning

confidence: 99%

What big eyes you have: the ecological role of giant pterygotid eurypterids

et al. 2014

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Eurypterids are a group of extinct chelicerates that ranged for over 200 Myr from the Ordovician to the Permian. Gigantism is common in the group; about 50% of families include taxa over 0.8 m in length. Among these were the pterygotids (Pterygotidae), which reached lengths of over 2 m and were the largest arthropods that ever lived. They have been interpreted as highly mobile visual predators on the basis of their large size, enlarged, robust chelicerae and forward-facing compound eyes. Here, we test this interpretation by reconstructing the visual capability of Acutiramus cummingsi (Pterygotidae) and comparing it with that of the smaller Eurypterus sp. (Eurypteridae), which lacked enlarged chelicerae, and other arthropods of similar geologic age. In A. cummingsi, there is no area of lenses differentiated to provide increased visual acuity, and the interommatidial angles (IOA) do not fall within the range of high-level modern arthropod predators. Our results show that the visual acuity of A. cummingsi is poor compared with that of co-occurring Eurypterus sp. The ecological role of pterygotids may have been as predators on thin-shelled and soft-bodied prey, perhaps in low-light conditions or at night.

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Section: Introductionmentioning

confidence: 99%

What big eyes you have: the ecological role of giant pterygotid eurypterids

et al. 2014

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“…Lebedev et al . ; Elliott and Petriello ). Lethal shell‐breaking predation is suggested by the occurrence of clusters of characteristically broken shells of modiolopsid bivalves and of cleft shells of conchostracans (cf.…”

Section: Discussionmentioning

confidence: 96%

Telltale eyes: the lateral visual systems of Rhenish Lower Devonian eurypterids (Arthropoda, Chelicerata) and their palaeobiological implications

Poschmann¹,

Schoenemann

McCoy

2016

Palaeontology

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The compound eyes of three taxa of Rhenish Lower Devonian eurypterids are examined and compared with those known from other eurypterids and the extant horseshoe crab Limulus polyphemus. The lateral eyes of the small species Rhenopterus diensti, a phylogenetically basal representative of the stylonurine clade, are characterized by a comparatively low number of lenses and high interommatidial angle Dφ (2.8°). The comparatively limited visual capacities of R. diensti are more similar to L. polyphemus than to its closer relatives of the eurypterine clade and perhaps this reflects a progression of lateral eye structure in the evolution of eurypterids as a whole. The number of eye facets in Adelophthalmus sievertsi is higher than that in the supposed ambush predator Acutiramus cummingsi, but lower than that in other 'swimming' eurypterids (Eurypterina).Due to poor preservation, no other eye parameters could be analysed in this species, but further morphological attributes and geographical distribution designate the mid-sized A. sievertsi as an able swimmer. A low interommatidial angle Dφ of less than 1°confirms that the visual capacities of Jaekelopterus rhenaniae are in line with an interpretation of this giant species as an active high-level predator. The inferred lifestyles of adult individuals of these three, co-occurring Rhenish eurypterids indicate niche differentiation avoiding to some degree the competition for food in their marginal marine to delta plain transitional habitats.

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“…The chelicerae of all studied species of Jaekelopterus, Pterygotus and IVPP-14593 are enlarged and robust with prominent, differentiated denticles and a curved free ramus, features associated with strong grasping and puncturing abilities in modern crustaceans [12] and scorpions [13]. Puncture wounds on the dorsal shield of a poraspid agnathan from the Devonian of Utah have been attributed to the chelicera of Jaekelopterus howelli [14]. The IOA values for this group fall within the range (,18) indicative of active, high level predators among modern arthropods (figure 2 and table 1) [7].…”

Section: Resultsmentioning

confidence: 99%

All the better to see you with: eyes and claws reveal the evolution of divergent ecological roles in giant pterygotid eurypterids

et al. 2015

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Pterygotid eurypterids have traditionally been interpreted as active, high-level, visual predators; however, recent studies of the visual system and cheliceral morphology of the pterygotid Acutiramus contradict this interpretation. Here, we report similar analyses of the pterygotids Erettopterus, Jaekelopterus and Pterygotus, and the pterygotid sister taxon Slimonia. Representative species of all these genera have more acute vision than A. cummingsi. The visual systems of Jaekelopterus rhenaniae and Pterygotus anglicus are comparable to that of modern predatory arthropods. All species of Jaekelopterus and Pterygotus have robust crushing chelicerae, morphologically distinct from the weaker slicing chelicerae of Acutiramus. Vision in Erettopterus osiliensis and Slimonia acuminata is more acute than in Acutiramus cummingsi, but not to the same degree as in modern active predators, and the morphology of the chelicerae in these genera suggests a grasping function. The pterygotids evolved with a shift in ecology from generalized feeder to specialized predator. Pterygotid eurypterids share a characteristic morphology but, although some were top predators, their ecology differs radically between genera.

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New poraspids (Agnatha, Heterostraci) from the Early Devonian of the western United States

Cited by 19 publications

References 23 publications

What big eyes you have: the ecological role of giant pterygotid eurypterids

What big eyes you have: the ecological role of giant pterygotid eurypterids

Telltale eyes: the lateral visual systems of Rhenish Lower Devonian eurypterids (Arthropoda, Chelicerata) and their palaeobiological implications

All the better to see you with: eyes and claws reveal the evolution of divergent ecological roles in giant pterygotid eurypterids

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